>>>>> "Tom" == Tom Lane <t...@sss.pgh.pa.us> writes:
>> Updated version of the aggregate order by patch. Tom> I'm starting to look at this now. I find it rather bizarre to Tom> merge both the actual arguments of an aggregate and the optional Tom> ORDER BY expressions into a single targetlist. It doesn't seem Tom> like that would be an especially convenient representation to Tom> work with, It's extremely convenient, since you need the arguments and the ordering expressions together in a slot in order to feed them to tuplesort (in the general case where there is more than one expression); you need a tupledesc to pass to tuplesort; and there are existing functions to construct all of these things from the tlist. Also, you want to merge the argument expressions and ordering expressions where possible, and this is exactly what the existing transformSortClause stuff expects. Tom> and I would also expect there to be a nonzero performance hit Tom> from the extra TargetEntry expression nodes, even when the Tom> feature is not in use. I tested for that and couldn't reliably detect any (certainly <2% on count(i) on generated data, and under the circumstances I was testing that's not necessarily outside the error margin). -- Andrew (irc:RhodiumToad) -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
